"If being a pedant means that you care passionately about the English language, then Bernard welcomes the charge," says Bernard Lamb's publicist.

For the past 40 years, Dr Lamb, emeritus reader in genetics at Imperial College London and president of The Queen's English Society, has been on a quest to improve standards of English among his students and the general population.

His latest book, The Queen's English: And How to Use it, published this week, explains why good English matters and how to achieve it.

Aside from the crucial fact that "there are thoughts that we cannot consciously have unless we have the right words and an ability to use them in coherent sentences", Dr Lamb points out that language also matters to employers.

His book cites the head of an online recruitment agency who reports that a third of job applications from graduates with good degrees from good universities are rejected because of poor English in their CVs. Too many people are "far too relaxed" about the issue, he believes.

In the 1970s, Dr Lamb was working with a Sri Lankan research student who politely pointed out that there was room for improvement when it came to his own spelling and grammar.

"I started learning the rules of spelling, using a dictionary more, learning about prefixes and suffixes, and playing Scrabble with the student," he explains.

She won the first 80 games - but the pair ended up as finalists in the national Scrabble championships.

A keen teacher, Dr Lamb then set out to improve his students' use of English.

"They were making really crucial errors, like writing, 'Bad diet effects a woman's pregnancy', which means it makes her pregnant, rather than it 'affects' her pregnancy. They wrote about 'complimentary' genes instead of 'complementary' genes."

One error he particularly enjoyed came from a student who wrote about a cow being fertilised by "seamen". But he still knocked a mark off: "It is bad science."

The Queen's English is peppered with cartoons and humorous examples of student "howlers".

When Dr Lamb introduced lectures for first-year biology students on how to write scientific English, the students "had a good laugh over the errors", but then promptly went and made them.

The best policy is for teachers to correct errors "in a kindly, constructive fashion" throughout the education system, he believes.

"If you make it clear to students that bad English leads to bad science, and bad science will be penalised, then they will do something about it. They don't like losing marks."

However, most university staff "totally ignore" errors of English, and some are unable to identify them, he fears.

At Imperial, he says, "the other staff really weren't that interested. You don't get promotions for doing things like that, you get promoted for your research publications. It is no one's priority at university."

Correcting also takes time, and teachers "want to be popular".

"If no one else does the correction, they stand out, and students think they are pedants. It is a matter of trying to change the culture."

To raise the profile of the issue, Dr Lamb has taken to running surveys of his students' errors. The results have attracted national publicity, including the headlines "Prof hits at spell shock" and "Tutor to shame students who just can't spell".

This got him into trouble with Imperial. "It wasn't the done thing to have any kind of criticism of our students," says Dr Lamb, whose other books include How to Write about Biology (1994). "I got into hot water. I made it clear that it isn't 'knocking our students', it is knocking general standards. I get on very well with my students and always have done," says Dr Lamb who, with his wife, held a dinner in his home each year for his personal tutees.

While some students have protested that it is "not his job" to correct their English, others have been very grateful, he says.

Dr Lamb, 68, joined The Queen's English Society in 1981 after seeing a notice in a newspaper. "I thought, 'A national organisation that fights for higher standards of English? I want to be part of it.'"

In his role as president, he lets people in the public eye know when they have made an error, and he has recently written to several national newspaper journalists.

"The more people who are fighting for good English, the better. It is in everyone's interest," he says.